High-reliability and low-dark-current 10-Gb/s planar superlattice avalanche photodiodes

For compact and high-sensitivity 10 Gb/s optical receiver applications, we have developed low-dark-current planar-structure InAlGaAs-InAlAs superlattice avalanche photodiodes with a Ti-implanted guard-ring, The APD's exhibited dark current as low as 0.36 mu A at a gain of 10, The temperature dependence of the dark current was confirmed to be in a sufficient level for practical 10-Gb/s applications, The APD's also exhibited a quantum efficiency of 67%, a gain-bandwidth-product of 110 GHz, a top 3-dB bandwidth of 15.2 GHz, and a minimum gain for 10-GHz bandwidth of 1.6, Preliminary aging test also showed a stable dark current operation after aging of over 2200 h at 200 degrees C, These high-reliability, low-dark-current, high-speed, and wide-dynamic-range characteristics are promising for 10-Gb/s high-sensitivity optical receiver use.